| Home | [1–10] << 11 12 13 14 15 16 17 18 19 20 >> [21–30] |
|
i Rios, J. F., & Houpt, K. (1995). Sexual behavior in geldings. Appl. Anim. Behav. Sci., 46(1-2), 133–135.
Abstract: Abstract
In response to a request published in Equus, a magazine for those interested in horses, 85 owners of older geldings exhibiting sexual behavior completed history forms. The mean age of geldings was 16 f 5 years. Only 39 of the owners had had the gelding for at least a year before the behavior was noted. These cases could be used to determine the true age of onset of the problem. When log survivorship was used to determine whether there were one or two different populations, a break or change in the slope at age 16 indicated that there are two populations. One population shows the behavior from the time of castration and the other first exhibits the behavior in old age, possibly in response to an ACTH secreting pituitary adenoma. A total of 40% of the horses were Quarterhorses, the most numerous breed in the US; 78% of the horses were purebreds. Fewer than half the owners knew the age at which their horse had been castrated because they did not own the horse at the time. The mean age at castration, when known, was 3.3 f 2.5 years. The reason for contacting us was sexual behavior (70%), aggression (24%). or some other problem ( 1 o/o). Whether or not aggression was the presenting problem, most of the horses showed aggression (95%), particularly towards other geldings (88%)) but also towards people (3 1%). Copulatory behavior (mounting) was shown by 69% of the geldings and half of those were able to intromit. These findings indicate that the sexual behavior of geldings is a problem for owners and that aggression usually accompanies sexual behavior. The owners were encouraged to send serum samples taken before and after human chorionic gonadotropin (HCG) administration for testosterone and estrone sulfate analysis to determine whether residual testicular tissue was responsible for the horse’s behavior. Of the 14 horses tested, only one had elevated levels of testosterone indicating that there was residual testicular tissue. A total of six of the owners agreed to treat their horses with cyproheptadine at a dose of 8 mg day- ’ gradually increased to 88 mg day- ’ per horse. A total of three of the horses showed a decline in sexual and aggressive behavior, one got worse and two had side effects and treatment was withdrawn. |
|
Barton, R. A., & Whiten, A. (1993). Feeding competition among female olive baboons, Papio anubis. Anim. Behav., 46(4), 777–789.
Abstract: Abstract. Competition for food is thought to play a key role in the social organization of group-living female primates, leading to the prediction that individual foraging success will be partly regulated by dominance relationships. Among adult females in a group of free-ranging olive baboons, dominance rank was significantly correlated with nutrient acquisition rates (feeding rates and daily intakes), but not with dietary diversity or quality, nor with activity budgets. The mean daily food intake of the three highest-ranking females was 30% greater than that of the three lowest-ranking females, providing an explanation for relationships between female rank and fertility found in a number of other studies of group-living primates. The intensity of feeding competition, as measured by supplant rates and spatial clustering of individuals, increased during the dry season, a period of low food availability, seemingly because foods eaten then were more clumped in distribution than those eaten in the wet season. Implications for models of female social structure and maximum group size are discussed.
|
|
Barton, R. A. (1993). Sociospatial mechanisms of feeding competition in female olive baboons, Papio anubis. Anim. Behav., 46(4), 791–802.
Abstract: Abstract. Social and spatial mechanisms of feeding competition among adult female olive baboons were studied in two free-ranging groups, one foraging for natural foods, and one that was being provisioned. Similar behavioural processes were found to underlie rank-related differences in food intake in the two situations. Dominance rank of females in the naturally foraging group was positively correlated with the rate at which other animals were supplanted from feeding sites, the ratio of supplants of others to supplants received, and the number of near neighbours while feeding on clumped foods. It is unlikely that the latter result was due to rank-related differences in matriline size, because no significant correlations between rank and neighbour density were found for non-feeding activities. Step-wise regression analysis indicated that both number of neighbours and the supplant ratio explained significant proportions of inter-individual variance in daily food intake, though only the supplant ratio contributed significantly to feeding rate. High-ranking females also had priority of access to feeding sites within trees, and competition was most intense for foods that were spatially clumped. Similarly, in the provisioned group, rank was correlated with the rate at which supplants were received, and with spatial indices estimating centrality and the area of unoccupied space around an individual. Over 99% of the inter-individual variance in feeding rate was explained in a step-wise regression with supplant rates and spatial indices as independent variables. It is concluded that both active supplanting and individuals' spatial positions within the group mediate rank-related differences in food intake.
|
|
Dugatkin, L. A., & Wilson, D. S. (1994). Choice experiments and cognition: a reply to Lamprecht & Hofer. Anim. Behav., 47(6), 1459–1461.
|
|
McLeod, P. G., & Huntingford, F. A. (1994). Social rank and predator inspection in sticklebacks. Anim. Behav., 47(5), 1238–1240.
|
|
Kaseda, Y., & Khalil, A. M. (1996). Harem size and reproductive success of stallions in Misaki feral horses. Appl. Anim. Behav. Sci., 47(3-4), 163–173.
Abstract: Over a 16-year period (1979-1994), long-term investigations were carried out on 14 Misaki feral stallions to analyze changes in harem size and the reproductive success. Harem size changed with the age of the stallions. Most stallions formed harem groups with four to five mares at the age of 4-6 and then the number of mares increased rapidly to the maximum at the age of 6-9 years. Thereafter, harem size decreased gradually to a minimum with advancing age. The harem size of 60 stable harem groups ranged from 1 to 9, and the average varied from a minimum mean of 1.8 in 1988 to a maximum mean of 5.3 in 1982. Mean harem size increased as adult sex ratio increased and a significant and positive correlation was found between them. One hundred and ninety-eight sire-foal pairs were determined by a paternity test with blood types and consort relations between stallions and mares during the study period. Out of 99 foals which were born in the stable harem groups, the true sires of 84 foals (85%) were the harem stallions in which the foals were born but the remaining 15 foals (15%) were sired by other harem stallions. Two out of three stallions which were studied throughout their lifetime produced 24 and 25 foals in 10 and 11 years of their reproductive lifespan, respectively. Another one produced only five foals in 6 years. The number of foals sired by the harem stallions was less than two over harem size 7 and some of the foals born in the harem were sired by other harem stallions. These results suggest that if a particular stallion monopolizes too many mares, he could not sire so many offspring because he could not always prevent his rival stallions from mating with his mares in wild or feral circumstances.
|
|
Heyes CM. (1994). Reflections on self-recognition in primates. Anim. Behav., 47, 909.
|
|
Pollard, J. C., & Littlejohn, R. P. (1996). The effects of pen size on the behaviour of farmed red deer stags confined in yards. Appl. Anim. Behav. Sci., 47(3-4), 247–253.
Abstract: To determine whether pen size affected the behaviour and welfare of farmed red deer confined temporarily in yards, four groups of ten 2-year-old stags were confined for 40 min or 2 days in each of spring and summer, in either large (5 m × 4 m ) or small (2.5 m × 4) pens. In the small pens, wall pacing and vertical/horizontal head movements at the walls were more frequently observed (P < 0.05) and were carried out by a greater percentage of the deer (P < 0.001), and distances between individuals were smaller (P < 0.01), than observations in the large pens. Aggressive activities varied seasonally, with head-butting and chasing being seen most frequently in the spring (P < 0.05) and biting and kicking being seen most frequently in the summer (P < 0.05), and the overall frequency of aggressive activities was low in summer. In spring, in small pens there were fewer threats to head-butt, head butts by moving animals, and less stepping activity than in large pens (P < 0.05). In summer, in small pens there were more threats to butt and more stepping activity than in the large pens (P < 0.05). In both seasons, aggressive activities were correlated with wall pacing (r = 0.58 and 0.55, respectively). It was concluded that the effect of pen size on the frequency and nature of aggressive and other activities varied seasonally. In order minimise aggression and stepping activity, small pens were favoured in spring and large pens were favoured in summer. However, in both seasons there were greater inter-individual distances and reduced pacing and head movements at the walls in large pens. This latter finding may indicate that the large pens were less aversive to the deer, regardless of season.
Keywords: Red deer; Handling; Density; Aggression; Farming
|
|
Avital, E., & Jablonka, E. (1994). Social learning and the evolution of behaviour. Anim. Behav., 48(5), 1195–1199.
Abstract: Abstract. In animals capable of learning from a parent or other individual, socially acquired behaviour can be transmitted through several generations. When the inheritance of variations in such behaviour is independent of genotypic variations, natural selection can operate on an additional level. Direct evolution of behaviour becomes possible, and this may alter the estimates of costs and benefits of behaviour patterns for the individual who transmits them. It is suggested that the effects of maternally transmitted behaviour contribute to the evolution of maternal behavioural strategies, and to the evolution of behaviour associated with male-female conflict.
|
|
Chase, I. D., Bartolomeo, C., & Dugatkin, L. A. (1994). Aggressive interactions and inter-contest interval: how long do winners keep winning? Anim. Behav., 48(2), 393–400.
Abstract: Abstract. Considerable evidence across many taxa demonstrates that prior social experience affects the outcome of subsequent aggressive interactions. Although the 'loser effect', in which an individual losing one encounter is likely to lose the next, is relatively well understood, studies of the 'winner effect', in which winning one encounter increases the probability of winning the next, have produced mixed results. Earlier studies differ concerning whether a winner effect exists, and if it does, how long it lasts. The variation in results, however, may arise from different inter-contest intervals and procedures for selecting contestants employed across previous studies. These methodological differences are addressed through a series of experiments using randomly selected winners and three different inter-contest intervals in the pumpkinseed sunfish, Lepomis gibbosus. The results indicate that a winner effect does in fact exist in pumpkinseed sunfish, but that it only lasts between 15 and 60 min. Based on these results, predictions about the behavioural dynamics of hierarchy formation are discussed, and it is suggested that it may be impossible, in principle, to predict the outcome of dominance interactions between some individuals before they are actually assembled to form a group. Finally, the possible mechanisms underlying the winner effect are explored.
|